The present invention relates to a recording apparatus and to a liquid ejecting apparatus of an ink jet type recording apparatus or the like for ejecting a liquid of ink or the like from a head thereof to eject to a target medium. Further, the invention particularly relates to a roller structure provided in the apparatuses.
Here, a liquid ejecting apparatus includes not only a recording apparatus of a printer, a copier, a facsimile or the like using an ink jet type recording head and ejecting ink from the recording head to record on a recording medium but also an apparatus of ejecting a liquid corresponding to a use thereof in place of ink from a liquid ejecting head corresponding to the recording head to a target medium in correspondence with the recording medium to adhere the liquid to the target medium.
As a liquid ejecting head, other than the recording head, there is pointed out a colorant ejecting head used for fabricating a color filter of a liquid crystal display or the like, an electrode (conductive paste) ejecting head used for forming an electrode of an organic EL display, a face light emitting display (EFD) or the like, a living body organism ejecting head used for fabricating a biochip, a sample ejecting head as a precision pipette or the like.
In a related ink jet printer, as shown by, for example, JP-A-2003-335430, there is adopted a method of fabricating a sheet discharge driving roller by molding a sheet discharge roller shaft with a resin and injecting elastomer thereon to form a roller forming portion, with an object of reducing cost. As shown by FIG. 8 through FIG. 10, a sheet discharge driving roller 100 is formed with 4 pieces of rotation stopping portions 105 in a projecting shape extended in an axial direction of a sheet discharge roller shaft 103 at portions thereof for bringing a roller forming portion 101 and the sheet discharge roller shaft 103 into contact with each other such that a shift of the roller forming portion 101 is prevented in a surrounding area of the sheet discharge roller shaft 103.
However, although at an initial stage of injecting elastomer to a surrounding area of the sheet discharge roller shaft 103, the roller forming portion 101 is formed in a cylindrical shape, when elastomer is shrunk by cooling, as shown by FIG. 9, portions in correspondence with 4 pieces of the rotation stopping portions 105 are constituted by a slightly projecting shape (shown more or less out of proportion in the drawing) since a rate of shrinking a thickness of a thick-walled portion is larger than a rate of shrinking a thickness of a thin-walled portion. Therefore, as shown by FIG. 10, a circularity of a section of the sheet discharge driving roller 100 is deteriorated to decrease an accuracy of feeding a sheet or to cause to skew the sheet.